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The timing of inhalation of hypertonic saline in people with cystic fibrosis

Review question

We reviewed the evidence about whether the timing (in relation to airway clearance techniques or in relation to time of day) of hypertonic saline (a strong, sterile, salt water solution) through a nebuliser improves the physical properties of sputum, stimulates cough, improves clinical outcomes (such as lung function), and improves the perceived effect of airway clearance techniques in cystic fibrosis.

Background

Regular inhalation of hypertonic saline improves the clinical outcomes of people with cystic fibrosis. It is not certain whether it is better to inhale hypertonic saline before, during or after clearing the airways with physical techniques, nor whether it is better to inhale it in the morning or in the evening. We looked for trials that compared these different timing regimens.

Search date

The evidence is current to: 19 December 2016.

Study characteristics

The review included two studies with 63 people with cystic fibrosis aged between 18 and 64 years of age. The studies looked at the impact of the timing of hypertonic saline inhalation in relation to airway clearance techniques. The studies reported immediate outcomes after inhalation of hypertonic saline before, during or after physical airway clearance techniques. Both studies were short, involving only one to three treatments of each timing regimen.

Key results

While outcomes such as lung function did not show any difference between the regimens, people with cystic fibrosis perceived that inhaling hypertonic saline before or during airway clearance techniques was more effective and satisfying than inhaling hypertonic saline after airway clearance. No studies comparing morning and evening inhalation were found. Because the long-term efficacy of hypertonic saline has only been established for twice-daily inhalations, clinicians should advise patients to inhale hypertonic saline twice daily. However, if only one dose per day is tolerated, the time of day at which it is inhaled could be based on convenience or tolerability until further evidence is available.

Quality of the evidence

Overall, the quality of the evidence was very good. The only issues perhaps affecting the quality related to the fact that it was not possible for participants to be blinded to the treatment they received. However, because the studies were short-term and most of the significant results were based on perceived efficacy, timing of administration of hypertonic saline needs further study.

Authors' conclusions:

People with cystic fibrosis could be encouraged to inhale hypertonic saline before or during airway clearance techniques to maximise perceived efficacy and satisfaction, even though these timing regimens may not have any better effect on lung function than inhalation after airway clearance techniques. Given the long-term efficacy of hypertonic saline has only been established for twice-daily inhalations, clinicians should advise patients to inhale hypertonic saline twice daily. However, if only one dose per day is tolerated, the time of day at which it is inhaled could be based on convenience or tolerability until evidence comparing these regimens is available.

To determine whether the timing of hypertonic saline inhalation (in relation to airway clearance techniques or in relation to time of day) has an impact on its clinical efficacy in people with cystic fibrosis.

Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register: 19 December 2016.

Selection criteria:

Any trial of hypertonic saline in people with cystic fibrosis where timing of inhalation was the randomised element in the studyprotocol with either: inhalation up to six hours before airway clearance techniques compared to inhalation during airway clearance techniques compared to inhalation up to six hours after airway clearance techniques; or morning compared to evening inhalation with any definition provided by the author.

Data collection and analysis:

Both authors independently assessed the trials identified by the search for potential inclusion in the review.

Main results:

The searches identified 97 trial reports which represented 46 studies, of which two studies (providing data on 63 participants) met our inclusion criteria. Both studies used a cross-over design. Both studies had low risk of all types of bias except the participants and the therapists who applied the treatments were not blinded. Intervention periods ranged from one treatment to three treatments in one day. The effects of the various regimens on lung function were non-significant. Satisfaction was rated significantly lower on a 100-mm scale when hypertonic saline was inhaled after the airway clearance techniques: mean differences 20.38 mm (95% confidence interval 12.10 to 28.66) compared to before airway clearance techniques and 14.80 mm (95% confidence interval 5.70 to 23.90) compared to during the techniques. Perceived effectiveness showed similar significant results. Other outcomes were unaffected by the timing regimen used. No trials compared morning versus evening inhalation of hypertonic saline.

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